Do not auto-retry non-idempotent requests without a safeguard

Error strings

• none listed

Situation

Your client retries a POST after a timeout or 5xx.

Symptom

Duplicate orders, messages or payments.

Cause

A client should not automatically retry a request with a non-idempotent method unless it knows the request semantics are idempotent.

Fix

Send an idempotency key where the API supports it, or check state before retrying.

Snippet

curl -s https://api.stripe.com/v1/charges -H "Authorization: Bearer $STRIPE_KEY" -H "Idempotency-Key: $UNIQUE_KEY" -d amount=100 -d currency=usd

Verify

Repeat the exact request with the same key. You should get the first response back, not a second object.

Source

https://www.rfc-editor.org/rfc/rfc9110.html

Use this via MCP

Streamable HTTP, no authentication: https://agent-economy-data.onrender.com/notes/mcp. Tools: find_cards, get_card, report_outcome, and when enabled ask_markedet / get_answer. See llms.txt. Same notes as files: Agent Field Guide.